apfstests/tests/xfs/311

#! /bin/bash
# FS QA Test No. 311
#
# Test to reproduce an XFS unmount crash due to races with directory readahead.
# XFS had a bug in which unmount would proceed with a readahead I/O in flight.
# If the unmount deconstructed the log by the time I/O completion occurs,
# certain metadata read verifier checks could access invalid memory and cause a
# panic.
#
#-----------------------------------------------------------------------
# Copyright (c) 2016 Red Hat, Inc.  All Rights Reserved.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation.
#
# This program is distributed in the hope that it would be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write the Free Software Foundation,
# Inc.,  51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
#-----------------------------------------------------------------------
#

seq=`basename $0`
seqres=$RESULT_DIR/$seq
echo "QA output created by $seq"

here=`pwd`
tmp=/tmp/$$
status=1	# failure is the default!
trap "_cleanup; exit \$status" 0 1 2 3 15

_cleanup()
{
	cd /
	rm -f $tmp.*
	_scratch_unmount > /dev/null 2>&1
	_cleanup_delay > /dev/null 2>&1
}

# get standard environment, filters and checks
. ./common/rc
. ./common/dmdelay

# Modify as appropriate.
_supported_fs xfs
_supported_os Linux

_require_scratch
_require_dm_target delay

rm -f $seqres.full

echo "Silence is golden."

_scratch_mkfs_xfs >> $seqres.full 2>&1

_init_delay
_mount_delay

# insert entries to grow the directory to at least one extent, which is what
# triggers readahead on dir open
mkdir $SCRATCH_MNT/dir
for i in $(seq 0 999); do
	echo > $SCRATCH_MNT/dir/$i
done

# remount to clear the buffer cache
_unmount_delay
_mount_delay

# introduce a read I/O delay
_load_delay_table $DELAY_READ

# Map the directory and immediately unmount. This should invoke an asynchronous
# readahead on the first block of the directory. The readahead is delayed by
# dm-delay. If the unmount doesn't properly wait for the readahead completion,
# the read verifier can run after core data structures have been freed and lead
# to a crash/panic.
$XFS_IO_PROG -c "bmap -v" $SCRATCH_MNT/dir >> $seqres.full 2>&1
_unmount_delay

_cleanup_delay

# success, all done
status=0
exit